Selective removal of CO2 from gaseous mixtures is of paramount importance for the purification of fuel gases such as methane and acetylene, and due to the imminent problem of anthropogenic CO2 emissions. Effective systems for CO2 removal must combine high selectivity and capacity with minimal energetic input to liberate the captured CO2. Materials presently used are amine solutions, zeolites, and porous membranes; but all fall short in one or more of these categories. To date, metal-organic frameworks (MOFs) have been shown to exhibit exceptional CO2 storage capacity under equilibrium conditions where pure CO2 is introduced into the pores. However, their capacities are dramatically reduced when exposed to mixtures of gases under dynamic conditions, as would be the case in power plant flue gas and methane mining applications. A useful measure of dynamic separation capacity is obtained by exposing the material to mixed gas streams and detecting the appearance or “breakthrough” of CO2 from the material.